<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>09_页面版心</title>
  <style>
    .main {
      background-color: lightgreen;
    }
    .center {
      width: 1000px;
      background-color: pink;
      margin: 0 auto;
    }
    .cart {
      width: 300px;
      height: 400px;
      border: 5px solid #000;
      background-color: orange;
      margin: 0 auto;
      text-align: center;
      line-height: 400px;
    }
  </style>
</head>
<body>
<div class="main">
  <div class="center">
    <div class="cart">我是卡片</div>
    <div class="cart">我是卡片</div>
    <div class="cart">我是卡片</div>
    <div class="cart">我是卡片</div>
  </div>
</div>
</body>
</html>